Present invention belongs to monolithic integrated circuits and buffers or current amplifiers in particular. For the base of this invention an insulated gate bipolar transistor (IGBT) technology has been taken, as the one which incorporates a field effect transistor (FET) and a bipolar transistor. It is widely known that a FET current ability is modest, so it is used in an IGBT for switching the bipolar transistor on and off, where the latter is able to provide high current characteristics.
However, due to an IGBT architecture, where the base of a bipolar transistor coincides with the drain of a FET in away that the collector of said bipolar transistor is positioned on the other side of the crystal with respect to said FET, it is not possible to achieve a multitude of IGBTs within a single integrated circuit. Switching of an IGBT is slow compare to a FET. Hence, our invention is aimed to allow integration of IGBTs into integrated circuits (IC), and for a significant raise of switching speed of said circuits. In order to achieve said improvements we offer a new architecture of an IGBT, where the drain of a FET is the base of a bipolar transistor and the collector of the bipolar transistor contains the source of the FET. In this way the whole circuit becomes very compact and very convenient to be multiplied within a single integrated circuit. To increase efficiency of the proposed circuit it should be completely isolated with a unipolar reinforced well with the bottom. This reinforced closure will limit the size of our circuit and reduce volume charge leading to a high switching performance. Constant closure voltage (all collectors at a rail voltage) will ensure that a surplus parasitic current goes between the rails rather than influences neighboring circuits.